Fuel nozzle for solid fuel injection engines



June 10, 1941. M. G. FIEI JLER FUEL NOZZLE FOR SOLID FUEL INJECTIONENGINES 4 Sheets-Sheet 1 Original Filed m 12. 19:57

June 10, 1941. M. G. FIEDLER 2,244,874

FUEL NOZZLE FOR SOLID FUEL INJECTION ENGINES Original Filed Nov. 12,1937 4 Sheets-Sheet 2 Agog M J69 Mar -aware June 10, 1941.

M. G. FIEDLER 2,244,874 FUEL NOZZLE FOR SOLID FUEL INJECTION ENGINESOriginal Filad NOV 12, 1937 4 Sheets-Sheet 3V June 10, 1941. M. e.FIEDLER FUEL NOZZLE FOR SOLID FUEL INJECTION ENGINES Original Filed Nov.12, 1937 4 Sheets-Sheet 4 I I. .IIII

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Patented June 10, 194} UNITED STATES PATENT OFFICE FUEL NOZZLE Fol: souFUEL nmzc'non m w 1 Max George Fiedler, Chester, Pa., assignor toFledler-Sellers Corporation, Philadelphia, Pa.,

a corporation of Pennsylvania Original application November 12, 1931,Serial No.

Divided and this application Septemher 7, 1938, Serial No. 228,875

3 (flaims. (Cl. 299-1075) This invention relates to compression ignitionengines of the oil-burning type, or that type usually referred to asDiesel engines, and more particularly to a method of operating theseengines in a manner such that they may operate on what is known as theOtto cycle; may be constructed and operate in the automotive speed sizesand ranges; and will operate without. detonation throughout such speedranges, and to provide a method of fueling the engine contributingprincipally to the attainment of the foregoing objects.

It is well known that the combustion of hydrocarbons may be either adirect oxidation or a 3 decomposition followed by oxidation of thedestruction products. In practice, there is a-race between the twoprocesses, the conditions being more favorable to hydroxylation when afuel has been properly divided and mixed with air 1 before it is burned,at which time the flame is blue and has no tendency to soot. Theconditions are more favorable to destructive combustion when the fuel isexposed very suddenly and in a highly vaporized condition to flametemperatures, the fuel particles decomposing rapidly before they canfind oxygen, and under these conditions there is a yellow radiationcaused by the burning carbon and a tendency to form soot.

some extent, by the compressionpressure. To a large extentthe ignitionlag in the engine is directly dependent upon the degree of turbulence,increasing with such turbulence due to the fact that the air usuallyrotates at high speed around the cylinder axis throwing the enteringfuel into the coldest zone adjacent the cylinder wall. This can only becounteracted through high com-,

pression and it follows that previous engines having high turbulencemust work under very high a compression pressures, oftenas high as 40.to50 atmospheres, and even under-these circumstances detonation frequentlyresults.

. is, inevitably, cracking. The combustion will,-

In the ordinary Diesel engine, air is compressed to the greatestpossible extentto prevent ignition lag, and a readily ignitible oilisemployed f the same reason. I havefound that in high speed Dieselengines having a high injection continues the air becomes saturated withthe products of combustion until the interference with furthercombustion is so serious that free carbon will begenerated. In theordifnary Diesel this occurs at a point where-approximately oftheavailable air has been consumed. The time necessary to establish theproper mixture for the first auto-ignition is equal to the ignition lagand influenced to a great ex- 1 tent by turbulence during injection, butalso by the shape of the combustion chamber, the-spray characteristics,duration of injection, and, to

Analyzing the standardspray characteristics as produced today in theusual solid fuel injection engines, it is found that the fuel,' throughbeing subjected to high injection pressures (3,000 to 20,000 lbs.) andthrough being forced through very small orifices is substantially in avapor stage. In addition to that, as has been photographically.demonstrated, the spray itself is very compact and cannot. be broken upeven by the most violent turbulence. This spray is, therefore, exposedto high compression temperatures without the ability to mixv with airand the :result therefore, follow the second type mentioned above andsince part of the combustion will be a hydrogen-oxygen or oxygen-methanereaction at. the high temperatures and pressures existing in Dieselengines, will, undoubtedly, be extremely violent and destructive.Furthermore, since the injection is through such fine orifices, theinjection period necessarily, and of course purposely under the Dieselsystem, continues after combustion hasactually begun and, obviously, the

later injected fuel will crack producing further.

hydrogen-oxygen reactions. I 4

I have discovered that proper operation may be provided by observing thefollowing precepts:

1. In small bore, short stroke engines the use of a-relatively largecombustion space and the maintenance of the air in this space in a highstate of turbulence in order that the mixture may be as complete andrapid as possible.

2. The instantaneous. or substantially instantaneous injection of thefuel into the combustion chamber, andv the use of lowcompressionpressures (approximately 240 pounds at the time of a startinginjection) thereby causing a combustion lag, in order that all of thefuel may be delivered thereto before combustion begins.

3. The introduction of the fuel spray into the combustion chamber in aform' in which.it is loosely and under relativelylow injecfor thecylinders."

cylinder l0.

tion pressures (preferably less than 1200 lbs.) thereby enabling thefuel to readily combine with the air in the combustion chamber and esadivision, and the fuel nozzle per-se forms the subject matter of thepresent application. .,'Ihese conditions may be satisfied by use of themethods hereinafter described and the-apparatus disclosed in theaccompanying drawings.

wherein: Y

Fig. 1 is a sectional view through an engine suitable for operation inaccordance with my invention;

Fig. 2 is a cycle diagram of the engine operation;

Fig. 3 is a conventional injection nozzle of the type at present in use;

Fig. 4 is a sectional view through a nozzle modified for use inaccordance with my invention;

Fig. 5 is a diagrammatic view illustrating the type of spray produced bythe nozzle of Fig. 4;

'Fig. 6 is a sectional view showing a preferred type of nozzle'and thepump connection thereto;

Fig. 7 is a highly enlarged sectional view through a portion of thenozzle of Fig. 6;

Figs. 8 and 9 are card diagrams showing operation of the engine with theordinary type of injection; and

Figs. 10 and 11 are card diagrams taken under identical conditions withthose in Figs. -8 and 9, but with use of the-new type of injection andoperation.

In attaining the first'of these precepts it is possible, and preferable,to employ, particularly where small-bore,short-stroke engines are beingutilized, a structure such as shown in Fig. 1 comprising, briefly, aworking cylinder It), a supercharging cylinder 1 l, a common crank shaft12 controlling the operation ofthe pistons l3 and M of these cylinders,and a common crank case i5 Communication between the upper ends of thecylinders is through a valve I6, disclosed as of the rotary type,preferably so arrangedthat the valve itself acts as a storage reservoirfor the final compression of the supercharging cylinder and subsequentlydelivers the stored pressure to the working cylinder at the beginning ofthe compression stroke thereof. As shown in the drawings, thecompression space I1 is relatively large as compared with-that of theusual compression ignition type engine, and

the supercharging cylinder is of ,such size that compressionignition'pressures may be provided inthis chamber but of a comparativelylowrorder.

scavenging of the working. cylinder is attained by injecting aircompressed in the crank case l5 by the simultaneous downward movement ofthe .pistons l3 and H, there being a port. is which,

when the piston I4 is in itslowermost position, places in communication,through an opening IS in the piston of the 'supercharging cylinder, theinterior of the crank case and the interior of Relatively highlycompressed air provided "through compression by bothpistons highdegree'of turbulence which is maintained until the working piston hasagain passed through its compression stroke with the supercharging andthe charge has been admitted as hereinafter described. Thus, while alarge volume of air is retained in the cylinder, 2. charge completelysufficient to the needs of the injected fuel, this charge is maintainedin a highly turbulent state, insuring a substantially instantaneouscomplete mixture of the air with the injected fuel.

The second precept may, obviously, be obtained in a variety of fashionsas, for example, by multiplying the number of nozzles employed andthereby increasing the effective injection area so that the periodnecessary to injection of a predetermined amount of fuel may be reducedto the desired point. I have found that the injection period should notexceed 10 of crank travel, and preferably should be confined toapproximately 7 thereof. Since the engine is now to operate as aconstant volume engine, all of the fuel being injected before ignition,it is, of course, desirable that this fuel be entered prior to thearrival of the working piston I 3 at top dead center, the arrangementbeing preferably that illustrated in the cycle diagram forming Fig. 2,in which the injection is illustrated as occurring in advance of the topdead center, a distance'corresponding to the average combustion lag.While the injection period might be delayed beyond the pointillustrated, this will, obviously, result in a loss of efiiciency, theoperation of the engine under such circumstances being substantiallythat of gasoline engines operating with aretarded spark. The compressionpressure of the engine must be kept sufiiciently low to insure acombustion lag enabling complete injection of the charge prior toinitial combustion, and must be sufficiently rapid to insure againstvapor formation. It will be noted that this is directly contrary toDiesel practice in which the production of highly vaporized sprays issought and in which the compression pressures are carried to the highestpossible point in order to avoid ignition lag. My invention, as so fardescribed, is disclosed in my prior United States application forpatent, Serial No. 34,134, filed July 31, 1935, entitled Engine.

Such an arrangement as that already suggested will result in .a highlyimproved operation of the engine, but to insure complete elimination ofdetonation, a smooth operation of the engine over a wide speed range,and an economical fuel injection system, the construction should be re--stricted to a single injection nozzle of peculiar characteristics. As iswell known to those familiar with Diesel construction as hithertopracorifices 20 (see Fig. 3). Due to the relatively large area of thelifting surface 2| provided on ticed, the usual nozzle comprises a valvelifted up by the injection pressure and thus permitting the escape ofthe fuel to the cylinder through such valves, with the attainment ofinjection swirls violently in the cylinder Ill, setting up a chatteragainst the seat or rather upon the fluid passing over this seat,reducing the fuel to a foam which is discharged through the openings 200at a much reduced pressure and in relatively large particles. Theincrease of the size of the openings c requires a thickening of the wallI! readily taken up and surrounded by the air in the combustion chambewith the'result that a thorough commingling is obtained, insuring properproportioning of air to fuel at the time the through-which theseopenings are formed in ormixture attains the flash point. As indicatedforded by the valve seat 24 and the valve 25 during the injectionperiod. It will be obvious that the valve, during the injection period,acts not only as a valve butlikewise as a flexible orifice, throughwhich the fuel may enter, exercising upon the fuel because of itsflexibility an agitating action producing a relatively loose foam. Thevalve seat itself should be of relatively large diameter in order toobtain large impact relief areas with a minimum lift and the valvespring should be strong enough so that at minimum pressure it willcounteract the inertia effect of the valve stem under impact andcontinually attempt to reseat the valve and thus produce the chatteringaction on the fuel passing over the seat. To

this end, as previously stated, a heavy valve spring having a highfrequency is preferable.

While the injection nozzle of Fig. 4 provides a highly improvedoperation, it was found in practice that this nozzle, after heating toapproximately 700 caused detonation. It was finally determined that thefoam formed in advance of' the nozzle tip by the chattering of the valveupon its seat tended to vaporize at the nozzle tip with resultingdetonation in operation. For this reason, the valve of Fig. 6 wasdeveloped. In this valve the lifting area is transferred to the centerof the valve, ports 2| communicating with a e 29 opening through thebottom of the valveand into'a chamber 3. at the nozzle tip. The valveseat is divided into two sections 3i and 32 by a groove 33 aligned withthe discharge ports 34. By this construction all foaming-fuel isdischarged from the valve and the tip of the nozzle is kept cool bymaintenance of a solid body of the fuel thereagainst. This valve, as inthe case of the valve of Figure 4, is maintained seated by a heavyhigh-frequency spring 35-;

Tests with an injection nozzle of this type. have proven conclusivelynot only its value in improving the explosion characteristics of theengine but likewise that for maximum efflciency certain definitecharacteristics and proportions should be employed in the injectionsystem exterior to the nozzle. I have found, for example, that theinjection at the nozzle is responsive not so much to the injection tothe system by a measuring pump of a predetermined amount of fluid as tothe impact resulting on the fluid line from the initial opening of thefuel line to receive the fuel displaced by the pump. This is'e'videncedby the fact that-the injection period does not appreciably vary througha considerable range of This is apparently due to the fact that with agreater fuel injection a greater residual pressure exists in the lineconnecting the pump and nozzle and, accordingly, the impact blowresulting on initial injection is transmitted with greater force to thevalve. The injection apparently immediately follows the closing I theintake openings 26 of the pump by the etch 21 thereof. The speed ofoperation ofthe pump piston apparently has little effect on theinjection ,although it is found that a greater fuel injection can beobtained through use of a relatively slow operation of the piston. Inactual use, sharp, medium and eccentric cams have been utilized,

and it is found that the eccentric cam gives muchv the best results, thesharp cam tending to upset equilibrium of the system. The indicationsare, accordingly, to the use of a large diameter pump omrated by aneccentric cam through a short 7 plunger travel.

I have, further, found that there are definite characteristics necessaryto the discharge line connectingthe pump and nozzle if proper injectioncharacteristics are to be obtained. For example, a discharge nozzlehaving openings of the size above mentioned employed in an engine of thecharacter described'must have a discharge line of definite length; inthe construction under test, .533 meter. It is found that a shorter linecauses double injection; that is to say, there are two definitelyseparated injection periods for each operation of the pump; apparentlycaused by the fact that the shorter line does not provide the dampeningeffect necessary and the impact blow becomes too great for the system.On the other hand, a longer line causes double injection, for. theapparent reason that there is too great a volume of liquid in the systemcausing a lag. It might appear that the presence of toomuch iluidin thesystem occasioned by the use of a long line might be overcome by areduction of the diameter of the discharge line, but thisis not thecase, for it is found that unless the diameter of the line is kept quitelarge the impact blow creates such high speed in the column that itcannot be controlled by the valve or flexible orifice. As a matter offact, I have found that a relatively large line as compared to thestandard line of 0 to 2 millimeters in diameter is essential of the sizeof the pump employed. For example,

aipump having a piston 10 millimeters in diameter provides an injectionrange between 10 and cubic millimeters, while with the same line andconditions a pump having a piston of 13 millimeters in diameter providesan injection range of between 10 and cubic millimetersin the sameinjection period.

I have determined that the temperature range at which injection shouldtake place in order to With the same noze permit the proper ignition lagenabling all of the fuel to be injected before combustion starts isprovided by a compression pressure having a minimum of 120 pounds persquare inch and a maximum of 400 pounds per square inch, the

' most efilcient range being between 330 pounds and 360 pounds to thesquare inch. In this range the temperatures are sufliciently high tocause rapid heating of the material and are at the same time belowthe.decomposition temperature when the, fuel is delivered th the cylinder inthe form of a coarse spray.

The vast improvement in operation of an engine in fuel injection underthe above-out lined circumstances as against the normal injec tionmethods may be visualized by comparing the indicator cards forming Figs.8 to 11. The indicator cards of Figs. 8 and 9 are cards taken from anengine utilizing the ordinary nozzle and developing a perfect highlyatomized compact spray in accordance with the principles of present-dayDiesel practice.

It will be noted that a succession of detonation peaks D appear evenwhen the engine is idling, as

' in Fig. 8.- These peaks are much exaggerated when the engine isoperating under load, as indicated at D'in Fig. 9. On the contrary, whenthe type of injection just described is employed in the same engine andunder the same conditions, these peaks immediately disappear and whenidling or under load the engine shows no tendency to the detonationsresponsible for these peaks. (See Figs. 10 and 11.)

Through the use of this method of fueling the engine and the nozzleconstruction hereinbefore described, Lam able to produce an engine whichis particularly adapted for use in automotive fields. In an engine fromwhich the indicator cards forming Figs. 10 and 11 were taken when usingthe new fueling system, such engine having 4 cylinders and a bore andstroke of 3% and 4" respectively excluding the exhaust port area, whenoperating at 1800 revolutions produced 150 H. P., and at 1,000revolutions produced 80 H. P. It is, however, operable in the higherautomotive ranges; thatis to say, 3,000 to 4,000 revolutions,

-It will be noted that an engine operated as above described operatesneither on the Diesel engine speed can be obtained. It differs from theOtto cycle both in the fact that the volume ascents of air introduced ismaterially increased, and that the fuel is separately injected.

Since b'oth the method illustrated and the construction described arecapable of considerable modification without departing from the spiritof the invention, I do not wish to be understood as limiting myself.thereto except as, hereinafter claimed.

I claim:

1. In fuel injection apparatus of the type d...- scrlbed, a body havinglarge discharge openings, seating means over which liquid fuel must passto reach said openings, a valve coacting with the seating means, meansto periodically deliver fuel to the body in a manner tending to unseatthe valve, and a spring tending to seat the valve, said dischargeopenings being of such size, andthe lifting area of the valve subjectedto the fuel pressure and said spring being so proportioned and arrangedthat, at the selected injection pres= sure of the fuel, the fuelpressure is released im-= mediatelyupon unseating of the valvewherebythe valve is caused to chatter on the fuel during the delivery period.

2. In fuel injection apparatus for engines, a body having largedischarge openings, seating means over which liquid fuel must pass toreach said openings, a valve coacting with the seating means and havinga reduced pressure area, means to periodically deliver fuel to the bodyagainst said pressure area to unseat the valve, and a spring tending toseat the valve, said discharge openings being of such size, and the areaof the valve subjected to the fuel pressure and said spring being soproportioned and arranged that, at the selected injection pressure ofthe fuel, the

' fuel pressure is released immediately upon unseating of the valvewhereby the valve is caused to chatter on the fuel during the deliveryperiod and the fuel is injected as a loose foamy mass of liquidparticles.

3. In fuel injection apparatus for internal combustion engines, a bodyhaving large discharge openings, seating means over which liquid fuelmust pass to reach said openings, a spring seated valve coacting withthe seating means and having a reduced pressure area, means toperiodically deliver fuel to the body against said pressure area in amanner tending to unseat the valve against the action of said spring,said discharge openings being of such size, and the lifting area of thevalve subjected to the fuel pressure and said spring being soproportioned and arranged that at the injection pressures of the fuel ofthe order of not more than 1500 pounds to the square inch the fuelpressure is released immediately upon unseating of the valve wherebythevalue is caused to chatter on the fuel during the delivery period.

MAX GEORGE FIEDLER.

